1. Field of the Invention
The present invention relates to a lensed polarization maintaining fiber and its manufacturing method as well as a semiconductor laser module using the same and its manufacturing method.
2. Description of the Related Art
There are a variety of polarization maintaining fibers (PMFs) such as the PANDA fiber and jacket core fiber, which are designed to maintain the polarization of the light propagating through these fibers.
Some of those polarization maintaining fibers are lensed polarization maintaining fibers of which fiber ends are formed into lens shapes to provide high light-coupling efficiency when light is incident upon the fiber end.
With regard to those fibers of which fiber ends are formed into wedge-like lens shapes, Japanese Patent Laid-Open Publication Nos. 2000-28852 and 2000-221341 have disclosed a configuration in which the stress-applied regions are laid on the ridgeline of the wedge.
An object of the present invention is to provide a lensed polarization maintaining fiber of stable quality and its manufacturing method. The other object of the present invention is to provide a semiconductor laser module using such a lensed polarization maintaining fiber and its manufacturing method.
A first aspect of the present invention is to provide a lensed polarization maintaining fiber having a lens on an end thereof, the fiber comprises a core, a pair of stress-applied regions, the stress-applied regions disposed on both sides of the core, respectively, and a clad containing the core and stress-applied regions. The lens has at least an inclined face, the inclined face including an edge, each of the stress-applied regions being exposed on the inclined face except the edge.
A second aspect of the present invention is to provide a method for manufacturing a lensed polarization maintaining fiber having a lens on an end thereof, the method comprising the steps of forming a fiber end by cleaving a polarization maintaining fiber having a core, a pair of stress-applied regions disposed on both sides of the core, respectively, and a clad containing the core and stress-applied regions, and forming the fiber end into the lens. The lens has at least an inclined face, the inclined face including an edge, each of the stress-applied regions being exposed on the inclined face except the edge.
A third aspect of the present invention is to provide a semiconductor laser module comprises a package, a semiconductor laser device housed in the package, the semiconductor laser device having an active layer and a laser beam emitting face including one end of the active layer, and a lensed polarization maintaining fiber having a lens on one end thereof. The lens is opposed to the beam emitting face for receiving light emitted from the laser device and guiding the light to an outside of the package. The fiber comprises a core, a two stress-applied regions disposed on both sides of the core, respectively, and a clad containing the core and stress-applied regions. The lens has inclined faces, each of the stress-applied regions being exposed within one of the inclined faces.
A fourth aspect of the present invention is to provide a semiconductor laser module manufacturing method comprising the step of fixing a semiconductor laser device the semiconductor laser device having an active layer and a laser beam emitting face including one end of the active layer, and a lensed polarization maintaining fiber having a lens on one end thereof, the light emitting face being opposed to an end of the fiber. The fiber comprises a core, a two stress-applied regions disposed on both sides of the core, respectively, and a clad containing the core and stress-applied regions. The lens has inclined faces, each of the stress-applied regions being exposed within one of the inclined faces.